We used to use ARM proprietary C compilers at my last job doing firmware. Every time a compiler bug was fixed in one version to the next a new one was introduce

We used to use ARM proprietary C compilers at my last job doing firmware. Every time a compiler bug was fixed in one version to the next a new one was introduced. So we ended up sticking with a particular version that worked well and keep evaluating new ones till a better one is found. And we paid tons of money for the compilers and support contract back then. Maybe the situation is better these days.